LASIK and Corneal Thickness

If you are interested in undergoing LASIK surgery, there are a number of requirements that you must meet in order to be considered a good candidate for the procedure. One factor that contributes to the success of LASIK surgery is corneal thickness. During LASIK surgery, an incision is made in the outer layer of the cornea, and the underlying corneal layers are reshaped to produce clear vision in patients. However, in some patients, the cornea is too thin, increasing the risk of post-surgical LASIK complications.

In this blog post, Dr. Jerry Maida and the team at Maida Custom Vision discuss LASIK and corneal thickness requirements. Contact our Jacksonville, FL practice to undergo a LASIK evaluation, during which we will measure your corneal thickness and determine if you are a good candidate for treatment.

Corneal Thickness Requirements

During your LASIK evaluation, we will measure the thickness of the cornea with the corneal pachymetry test. The testing device is placed against the eye while the patient stares straight ahead and does not blink. The test employs the use of ultrasonic technology to measure corneal thickness.

During your LASIK screening, we will also perform a refraction test, which measures the degree of your refractive errors. Your LASIK surgeon will use the corneal thickness measurement, along with the results of your refraction test, to determine how much corneal tissue will remain after LASIK surgery. If patients will have a minimum of 250 microns of corneal tissue left, they will be approved for LASIK surgery, provided they meet all of the other requirements for surgery.

So, you may be wondering, how much corneal tissue is affected during LASIK surgery? Here is how it breaks down:

The corneal flap is typically about 160 microns thick

For every one diopter of prescription power, 12 to 14 microns of corneal tissue are removed

For example, if you have 3 diopters of refractive error, 160 microns would be used for the corneal flap and 36 to 42 microns would be removed. This totals 196 to 202 microns of corneal tissue. In the average patient, the cornea is 540 to 560 microns thick. In this case, that would leave at least 338 microns of corneal tissue remaining, well above the 250 microns minimum. However, in a patient that has naturally thin corneas or a very high prescription, he or she may not have enough corneal tissue left after LASIK surgery.

LASIK Alternatives

If you do not have adequate corneal thickness to undergo LASIK, you do have other options. Glasses and contact lenses can be worn to help you achieve clear vision. If you wish to undergo a surgical and more permanent vision correction option, we also offer PRK. PRK does not require the use of the corneal flap, so patients with thin corneas may qualify for this procedure. During PRK, the outer layer of the cornea, the epithelium, is removed. The underlying cornea can then be reshaped to produce clear vision. After surgery, the epithelium grows back, aided by the use of special contact lenses. PRK is associated with a longer healing time, but the results are comparable to that of LASIK.